PROS1 and antiphospholipid syndrome: However, vitamin K antagonists are the treatment of choice for antiphospholipid syndrome, protein S or protein C deficiency, while DOAC's use is still controversial.38, 39, 40, 41Additional studies designed to evaluate the efficiency of DOAC-Stop® treatment with a larger range of DOAC's concentration on more coagulation tests (including clotting factors and instruments using optical clot detection) will also be useful.